Study On The Fault Diagnosis Of Air-fuel Ratio Control System Electronic Controlled Gasoline Injection Engine Based On Signal Wavelet Analysis Method

This dissertation formulates the development and actuality of the electronic controlled gasoline engine, introduces the approach and method of diagnosis this kind of engine, and some advert proceeding.The Air-fuel ratio control system is the important composing part to pledge its fuel economy, low emission and good driveability. The principle and control process are very important to run engine normally. Oxygen sensor stakeout to oxygen in let gas simultaneity is the key link for A/F ratio control system confect mixed gas logically. The emphases of this dissertation are to research the change characteristic of oxygen sensor with engine running and the control bound. Through simulation experimentation, this dissertation tries to find the method of diagnosis engine by oxygen sensor.Through the analyse of natural and exceptional wave shape of oxygen sensor collected by digital memory oscillograph, the wave shape analyse method is proved exactly and fast in practice. The wavelet analysis method qua complementarity to wave shape analyse method, has function of wiping off yawp and discern character. So it can become gist to diagnosis engine malfunction.